PEORIA — The first crop of medical marijuana won't be available in Illinois for months, but the prospect of that harvest has already highlighted a glaring contradiction in state statutes.

The Illinois Medical Cannabis Pilot Program for the first time allows legal consumption of marijuana, while the state's vehicle code prohibits motorists from having any trace of the drug in their system while behind the wheel.

A Peoria attorney who specializes in medical marijuana issues is advocating for changes to the drugged driving statute to accommodate the new reality, and at least one bill has been proposed in Springfield to address the topic.

"There needs to be much done in perfecting the law and protecting the rights of drivers when it comes to investigating cannabis impairment," said Rodney Nordstrom, who is working with potential cultivation center and dispensary owners, as well as clients seeking to become qualifying medical marijuana patients.

Medical marijuana became legal in Illinois at the beginning of the year, but the administrative rule-making process that will create the framework for the system of growing and distributing marijuana and registering patients has delayed the drug's availability.

The Illinois Department of Public Health, which is responsible for administering the patient registration system, has posted draft rules for consideration by the Legislature's Joint Committee on Administrative Rules that address impaired driving in general terms.

Under those proposed rules, anyone who accepts a medical marijuana registry card agrees not to drive while impaired and consent to field sobriety tests by a police officer if asked, though possession of a registry card alone does not constitute sufficient suspicion for an officer to seek those tests.

Anyone who refuses the tests is subject to a 12-month suspension of driving privileges and revocation of the medical marijuana card. Those who submit to the test and show signs of impairment are subject to a six-month driver's license suspension.

The state relies on field sobriety tests developed by the National Highway Traffic Safety Administration to determine whether a motorist is impaired. The Illinois Vehicle Code recognizes those tests as adequate to establish impairment under the influence of any substance, but Nordstrom said the tests are mostly designed to detect alcohol intoxication.

If those tests indicate impairment, chemical tests follow. Unlike the drunken driving standard of 0.08 blood-alcohol content, however, there is no state law threshold for marijuana intoxication. The presence of any marijuana metabolites such as THC, the main psychoactive ingredient in the plant, makes a motorist subject to DUI prosecution.

Marijuana policy advocacy groups have argued that approach leads to false convictions because of the chemistry of marijuana's active ingredient. THC is fat soluble — rather than water soluble like alcohol, cocaine and heroin — and can stay in a person's system in measurable amounts for weeks after the last use.

Page 2 of 2 - "The state of Illinois has zero tolerance — right now, any amount of the drug in your system is a DUI," said Dustin Pierce, safety education officer for District 8 of the Illinois State Police. "It's definitely an issue on our radar."

A bill introduced earlier this month by state Sen. Kwame Raoul, D-Chicago, would strike the zero-tolerance provision from the Illinois Vehicle Code and specifically exempt medical marijuana cardholders from prosecution for having any amount of the drug in their system. The bill has been referred to the Assignments Committee.

The larger challenge will be establishing amounts of marijuana metabolites in blood, breath or urine that indicate levels of impairment that affect driving, said Tazewell County State's Attorney Stu Umholtz.

"What is the level that science would support as influencing someone's ability to operate a motor vehicle?" Umholtz asked.

Illinois could follow the lead of other states such as Colorado and simply set what is referred to as a minimum amount, similar to the current BAC standards for alcohol.

Now that Illinois residents could travel to other states such as Colorado and legally consume marijuana, it may make sense to have that standard apply to all Illinois motorists, rather than just those with medical marijuana cards, Umholtz said. That type of updated system could avoid prosecution of someone who legally consumes the drug out of state, then is involved in a traffic incident in Illinois days or weeks later.

"We ought to do the same thing with a substance that studies indicate is less detrimental (than alcohol)," Umholtz said. "We need to come up with a better system."

Matt Buedel can be reached at 686-3154 or mbuedel@pjstar.com. Follow him on Twitter @JournoBuedel.